This invention relates generally to polymer materials, and more particularly relates to techniques for synthesizing polymeric microstructures.
Polymeric microstructures are important for a wide range of applications, including MEMS, biomaterials, drug delivery, self-assembly, and other applications. The ability to controllably synthesize such microstructures, herein defined as structures having features in the size range of about 10 nm to about 1000 μm, is increasingly significant for enabling applications such as paints, rheological fluids, catalysis, diagnostics, and photonic materials. Monodisperse polymeric microstructures, herein defined as having a microstructure size distribution where >90% of the distribution lies within 5% of the median microstructure size, are particularly desirable as they can exhibit a constant and predictable response to external fields and can self-assemble in a predictable manner.
Conventionally, polymer microstructure synthesis is carried out by a batch process such as photolithography, stamping, or emulsion polymerization, or by an emulsion-based microfluidic technique such as flow-through microfluidic synthesis. Although these techniques have provided significant advances in microstructure synthesis, it is found in general that each limits microstructure composition and/or geometry. For example, photolithographic techniques generally limit the microstructure material to that which is compatible with a photolithographic process, e.g., requiring a photoresist as the structural material. Historically, the synthesis of polymeric microstructures with microfluidics has focused almost exclusively on spheroidal microstructures, in part because the minimization of microstructure interfacial energy leads to the formation of spheres or deformations of spheres such as rods, ellipsoids or discs, or cylinders.
In addition to these limitations in polymeric microstructure composition and geometry, conventional polymeric microstructure synthesis generally requires isotropic structural arrangements of materials. Further, the through-put of such processes is typically limited by a requirement for making one structure at a time or a limited photo-mask-defined field of structures at a time. These limitations in polymeric microstructure synthesis through-put, microstructure geometry, morphology, and functionality have restricted the ability to address the growing number of critical applications for which polymeric microstructures could be well suited.